that we need some sort of life cycle method where some logic should only run once, not more than once! we need to remember what we are exploring here. So we already have some options in the react hooks though. So despite the Hooks team's bold assertions, the fact is that there are times when I do need a constructor (or some equivalent). Nevertheless, there are certain times when I absolutely need logic to run before anything else in the life-cycle of this component, and I absolutely need to ensure that it will run once, and only once, for the entire life-cycle of this component. In fact, I'd say that the need for constructor-type logic is the exception, not the rule!!! To be clear, is a constructor usually needed in most components? No. #React constructor code#Code that runs once, and only once, for the entire life-cycle of this component.Code that runs before anything else in the life-cycle of this component.Specifically, when I think of a constructor, I think of these characteristics. The massive oversimplification in their dismissive FAQ overlooks the basic fact that there are other, perfectly-valid use-cases for a constructor (or, constructor-like functionality) that have nothing to do with initializing state variables. He just pats you on the head and says, "There, there. Just for fun's sake.It's like going to the dentist for a toothache - but the dentist doesn't fix the problem. This "answer" is arrogant because, based on its faulty assumptions, it boldly states that you don't need a constructor. that's sort of the wrong direction though!!!! This "answer" is ignorant because it assumes that the only reason for a constructor is to initialize state. It's similar to some of the other documentation I've seen around Hooks that makes all sorts of misguided assumptions for you. I don't know if this "answer" is ignorant. If computing the initial state is expensive, you can pass a function to state." You can initialize the state in the state call. "Constructor: Function components don’t need (emphasis: mine) a constructor. So I found the hype statement from one of the React documentation I was always wondering where's constructor gone during the transition to the react hooks from the class-based component? Because react hooks life cycle doesn't have a constructor and "How do lifecycle methods correspond to Hooks? But when I upgraded React to 16.8 a few months back and started exploring the functional component using react hooks. we usually need to start to define the constructor as the initial entry point for any local states and props for your component or page. It protects against setState() calls from render() but what really happens is one component causing a side effect in its constructor, leading to other component getting its setState() called.When you are building the react apps using the class-based components. This warning is misleading because this is not what happened. They will log a warning that setState() cannot be called from render(). If a constructor has side effects like a Redux / Flux Store dispatch, then other components may get their setState() called. As you all know we cannot call setState() in the constructor. ➁ Binding event handler methods to an instance.įetching data in constructor is considered to be a side effect and it is recommended to avoid that. ➀ Initializing local state by assigning an object to this.state. When loading initial data of app, many developers think that they can use constructor as we have been tought that constructor is used for initialization.Ī typical react constructor is used for two purpose. Lets consider another good candidate for making api call. I hope you are clear with this lifecycle.
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